Brake Drum Radial Runout Check - Off Vehicle

BRAKE DRUM RADIAL RUNOUT CHECK (OFF-VEHICLE)

1. Remove road wheel.
2. Remove brake drum and install on brake lathe.
3. Fasten a dial indicator to the lathe.
4. Position dial indicator tip against drum surface.
5. Rotate the drum to the lowest reading.
6. Zero the dial indicator.
7. Rotate the brake drum one complete revolution and observe Total Indicated Runout (TIR).
Maximum Radial Runout (Drum): 0.15 mm (0.006 inch)

REPLACING BRAKE DRUMS

NOTICE: When installing new brake drums, do not refinish the braking surface as these parts are at the correct level of surface finish.

REFINISHING BRAKE DRUMS
When performing routine brake maintenance, drums should not be refinished unless there is a brake pulsation caused by the drums or the drums are excessively scored.
If a drum is to be refinished, only enough metal should be removed to obtain a true, smooth braking surface. If a drum does not clean up when refinished to a maximum rebore diameter as shown in the specifications at the end of this section, it must be replaced. Removal of more metal will affect dissipation of heat and may cause distortion of the drum.
All brake drums have a maximum diameter cast into them. This diameter is the maximum wear diameter and not a refinish diameter. Do not refinish a brake drum that will not meet specifications. Any drum which exceeds the maximum refinish diameter after refinishing should be replaced.

CAUTION: WHEN REFINISHING DRUMS, ALWAYS USE SHARP CUTTING INSERTS (TIPS, BITS). DULL OR WORN TOOLS LEAVE A POOR SURFACE FINISH WHICH WILL AFFECT INITIAL BRAKING PERFORMANCE. VIBRATION DAMPENING ATTACHMENTS SHOULD ALWAYS BE USED WHEN REFINISHING BRAKING SURFACES. THESE ATTACHMENTS ELIMINATE TOOL CHATTER AND WILL RESULT IN BETTER SURFACE FINISH. FOLLOW ALL THE BRAKE LATHE'S MACHINING INSTRUCTIONS TO OBTAIN THE BEST POSSIBLE SURFACE FINISH QUALITY.